To get the list of available functions in your running Neo4j instance, you can use the following:
CALL dbms.functions()
The default installation (without plugins) already contains some functions – for instance, the randomUUID function.
The result of a function is accessible through a normal Cypher query. For instance, to generate a random UUID, you can use the following:
RETURN randomUUID()
This can be used to generate a random UUID when creating a node like this:
CREATE (:Node {uuid: randomUUID()})
A new node will be created with a property uuid containing a randomly generated UUID.